The following report on Allied use of searchlights to illuminate battlefields in WWII is taken
from Tactical and Technical Trends,
No. 57, April 1945.

[DISCLAIMER: The following text is taken from the U.S. War Department
publication Tactical and Technical Trends. As with all wartime
intelligence information, data may be incomplete or inaccurate. No
attempt has been made to update or correct the text. Any views or
opinions expressed do not necessarily represent those of the website.]

"Artificial Moonlight"

Allies Illuminate Night Battlefields

Allied troops in France and Italy are making effective use of "artificial
moonlight," produced by antiaircraft searchlights, for night operations
and movements.

The term "artificial moonlight" has been coined to distinguish searchlight
illumination from normal moonlight, which is referred to as "movement
light" in night operations.

Considerable future development may be expected in the tactical use of
mobile searchlights to assist ground operations during darkness. Artificial
moonlight introduces a wide field for ingenuity, since a fairly wide variation
of lighting effects is possible to suit particular requirements in almost
any weather.

British reports indicate success in the use of searchlights to illuminate
battlefields in Italy. Indirect lighting facilitated the movement
of tanks, infantry, and motor transport, as well as other activities
that required a degree of illumination at night.

On the Gothic Line in Italy the searchlights were sited 5,000 to 8,000 yards
behind the front lines and usually near the top of reverse slopes. A battery
of 24 lights had a maximum frontage of 5,000 yards. Sixteen lights
covered 3,000 to 4,000 yards and eight lights 1,000 to 1,200 yards. However, these
frontage figures do not include a much larger area in which movement was aided
by diffusion of the light.

British searchlights also were used on several occasions in France, in some
cases closer to the front lines than in Italy. Instances have been reported
where the lights were placed 4,000 to 6,000 yards behind the front line, in
defilade, and adjusted on low clouds to give reflected light equal to that
of a half-moon.

In France the use of artificial moonlight simplified and expedited
removal of minefields at night, made blackout driving easier, and aided
in detecting and defeating German patrols. In addition, engineers
were able to make emergency road repairs in forward areas at night. Since
the Germans faced the searchlights, the light did not aid them as much
as the Allied troops, who had their back to the source of light. Furthermore, even
in diffused light, a considerable shadow effect was produced on the far side of
hedges, tanks, and houses. From the concealment of these shadows Allied troops
could observe German troops and installations, which were thrown into relief.

German Reactions

German prisoners of war who have faced Allied artificial moonlight differed
widely in their opinions of its advantages and disadvantages. The Germans
reasoned that the Allies had introduced the use of artificial moonlight to
direct artillery fire and naval gunfire; to illuminate target areas; to show
Allied aircraft the location of friendly troops; and to help Allied infantry
pick out German defenses.

The Germans claimed that the searchlight illumination aided their sentries
and outposts in detecting the approach of Allied infantrymen; that withdrawing
movements were aided, especially in bad weather; and that would-be deserters
were deterred by fear of being detected by their own troops.

Although few Germans admitted finding artificial moonlight a serious handicap, there
was one fairly general statement among the many conflicting ones: that
artificial moonlight has a definite nuisance value. The majority of German
troops felt decidedly uneasy during the period of illumination, not only
because of the uncanny atmosphere, but also because they felt that they were
now handicapped even during what used to be their one period of free movement.

The German viewpoint was that the advances of Allied infantry were made easier
by artificial movement light, not only because the attackers were able to see
where they were going, but also because the shadows offered concealment and
were so "unnatural" as to deceive the defenders.